What's a good WTS value?

I posted this question in the "software" category but didn't get much of a response... maybe it was the wrong category to ask the question so I decided to post it again in this category to see if anyone can help.

I was surfing the net about "WTS" and saw a site that a value of 25-30 is what most profitable players have. Lower than that you're folding too much, higher than that you're calling too much. But on the Elephant Software that value is considered "often/too often" which I've always interpreted as being loose. My WTS on the software is only 18-19. So I've been trying to get to the river more but the highest I've ever gotten it was 21.

So my first question is does that WTS=25-30 for a good player sound right, if not what would that range be?

And my second question is what exactly does a 19 WTS value mean in the Poker Elephant software? Is it 19% of the time I'm in the hand I go to showdown?